<!-- 热销商品图表 -->
<template>
  <div class="com-container">
    <div class="com-chart" ref="hot_ref"></div>
    <span class="iconfont arr-left" @click="toLeft" :style="comStyle">&#xe6ef;</span>
    <span class="iconfont arr-right" @click="toRight" :style="comStyle">&#xe6ed;</span>
    <!-- 右下角文字 -->
    <span class="cat-name" :style="comStyle">{{ catName }}</span>
  </div>
</template>

<script>
import { mapState } from "vuex";
import { getThemeValue } from '@/utils/theme_utils'
export default {
  data() {
    return {
      chartInstance: null,
      allData: null,
      currentIndex: 0, // 当前所展示的一级分类数据
      titleFontSize: 0,
      comStyle:'',
      catName:''
    };
  },
  computed: {
    catName() {
      if (!this.allData) {
        return "";
      } else {
        return this.allData[this.currentIndex].name;
      }
    },
    comStyle() {
      return {
        fontSize: this.titleFontSize + "px",
        color: getThemeValue(this.theme).titleColor
      };
    }
  },
  mounted() {
    this.initChart(); // 初始化echarts实例对象
    this.getData(); // 获取服务器数据
    window.addEventListener("resize", this.screenAdapter);
    this.screenAdapter();
  },
  destroyed() {
    window.removeEventListener("resize", this.screenAdapter);
  },
  methods: {
    initChart() {
      // 参数1：dom元素。参数2：主题（可选可不选）
      this.chartInstance = this.$echarts.init(this.$refs.hot_ref, this.theme);
      const initOption = {
        title: {
          text: "▍ 热销商品的占比",
          left: 20,
          top: 20
        },
        // 图例
        legend: {
          top: "85%",
          icon: "circle",
        },
        // 工具提示
        tooltip: {
          show: true,
          formatter: arg => {
            // console.log(arg);
            const thirdCategory = arg.data.children;
            // 计算出所有三级分类的数值总和
            let total = 0;
            thirdCategory.forEach(item => {
              total += item.value;
            });
            let retStr = "";
            thirdCategory.forEach(item => {
              retStr += `
                ${item.name}:${parseInt((item.value / total) * 100) + "%"}
                <br/>
                `;
            });
            return retStr;
          }
        },
        series: {
          type: "pie",
          label: {
            show: true
          },
          emphasis: {
            label: {
              show: true
            },
            labelLine: {
              show: false
            }
          }
        }
      };
      this.chartInstance.setOption(initOption);
    },
    // 发送请求，获取数据
    async getData() {
      const { data: ret } = await this.$http.get("hotproduct");
      this.allData = ret;
      // console.log(this.allData);
      this.updateChart(); // 获取服务器数据，对this.allData进行赋值之后，调用updateChart方法更新图表
    },
    // 更新图表配置项
    updateChart() {
      // 图例数据
      const legendData = this.allData[this.currentIndex].children.map(item => {
        return item.name;
      });

      const seriesData = this.allData[this.currentIndex].children.map(item => {
        return {
          name: item.name,
          value: item.value,
          children: item.children
        };
      });
      const dataOption = {
        legend: {
          data: legendData
        },
        series: [
          {
            data: seriesData
          }
        ]
      };
      this.chartInstance.setOption(dataOption);
    },
    // 分辨率大小
    screenAdapter() {
      this.titleFontSize = (this.$refs.hot_ref.offsetWidth / 100) * 3.6;
      const adapterOption = {
        title: {
          textStyle: {
            fontSize: this.titleFontSize
          }
        },
        legend: {
          itemWidth: this.titleFontSize,
          itemHeight: this.titleFontSize,
          itemGap: this.titleFontSize / 2,
          textStyle: {
            fontSize: this.titleFontSize / 1.5
          }
        },
        series: [
          {
            radius: this.titleFontSize * 4.5,
            conter: ["50%", "60%"]
          }
        ]
      };
      this.chartInstance.setOption(adapterOption);
      this.chartInstance.resize();
    },
    toLeft() {
      this.currentIndex--;
      if (this.currentIndex < 0) {
        this.currentIndex = this.allData.length - 1;
      }
      this.updateChart();
    },
    toRight() {
      this.currentIndex++;
      if (this.currentIndex > this.allData.length - 1) {
        this.currentIndex = 0;
      }
      this.updateChart();
    }
  },
  computed:{
    ...mapState(['theme'])
  },
  watch:{
    theme(){
      console.log('主题切换了');
      this.chartInstance.dispose()  // 销毁当前图表
      this.initChart() // 重新以最新的主题名称初始化图表对象
      this.screenAdapter() // 完成屏幕的适配
      this.updateChart() // 更新图表的展示
    }
  }
};
</script>

<style lang="less" scoped>
// 左边箭头
.arr-left {
  position: absolute;
  left: 10%;
  top: 50%;
  transform: translateY(-50%);
  cursor: pointer; // 鼠标小手
  color: white;
}
// 右边箭头
.arr-right {
  position: absolute;
  right: 10%;
  top: 50%;
  transform: translateY(-50%);
  cursor: pointer;
  color: white;
}
.cat-name {
  position: absolute;
  left: 80%;
  bottom: 20px;
  color: white;
}
</style>
